The UK-CDI - Inter-dialect differences in English language CDI datasets.

Alcock, K. J., Rowland, C., & Meints, K. (2018). The UK-CDI - Inter-dialect differences in English language CDI datasets. Paper presented at the European Network Meeting - Communicative Development Inventories, Dubrovnik.


Objectives: to replicate US/UK differences found in Communicative Development Inventory (CDI, a parent-completed vocabulary checklist) scores in 8-18 month-olds.  

Design: parents of infants aged 8-18 months completed the UK-CDI Words and Gestures (W&G), a 395- word checklist. Parents indicated whether their child understands each word, or understands and says the word.

Methods: a total of 1600 parents completed the UK-CDI W&G. Parents were recruited through parent groups and centres, UK babylabs, the NHS, and social media. The sample was balanced by Index of Multiple Deprivation quantile and other SES measures. Smoothed medians for each month of age were compared to existing medians from the MacArthur-Bates CDI(W&G), the US version of the CDI.

Results: UK children’s scores on comprehension and production were lower than the US scores; for example at 13 months the median UK toddler understands 87 words while a comparison US toddler understands 97 words. However, the differences were not significant across age groups neither were they as large a magnitude as the Oxford-US comparison from Hamilton et al (2000).

Conclusions: Our UK-CDI (W&G) scores are lower than the US scores, but not significantly lower as the Oxford scores are. Hamilton et al state that their sample is middle class. It is therefore surprising that our comparison shows a smaller difference. The Oxford parents may be under-reporting vocabulary due to most participating in a lab study and being subject to experimenter scrutiny. Our sample may still under-report slightly due to cultural issues such as British reticence.